1. Field
The present invention relates generally to wireless communications and more specifically to feedback reporting in wireless communications systems.
2. Background
In recent years, communication systems' performance and capabilities have continued to improve rapidly in light of several technological advances and improvements with respect to telecommunication network architecture, signal processing, and protocols. In the area of wireless communications, various multiple access standards and protocols have been developed to increase system capacity and accommodate fast-growing user demand. These various multiple access schemes and standards include Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Code Division Multiple Access (CDMA), and Orthogonal Frequency Division Multiple Access (OFDMA), etc. Generally, in a system which employs TDMA technique, each user is allowed to transmit information in his assigned or allocated time slots whereas an FDMA system allows each user to transmit information on a particular frequency that is assigned to that particular user. A CDMA system, in contrast, is a spread spectrum system which allows different users to transmit information at the same frequency and at the same time by assigning a unique code to each user. In an OFDMA system, a high-rate data stream is split or divided into a number of lower rate data streams which are transmitted simultaneously in parallel over a number of subcarriers (also called subcarrier frequencies herein). Each user in an OFDMA system is provided with a subset of the available subcarriers for transmission of information.
In connection therewith, various domestic and international standards have been established including Advanced Mobile Phone Service (AMPS), Global System for Mobile (GSM), and cdmaOne.
Code division multiple access (CDMA) technology was introduced in cellular systems in the early 1990s with the development of the IS-95 standard. The IS-95 system has significantly evolved and matured in the last decade resulting in the enhanced revisions IS-95 A and B in 1994 and 1998, respectively. The IS-95-A/B and several related standards form the basis of the second generation cellular technology which is also known as cdmaOne.
The 3G evolution of cdmaOne consists of a family of standards, known as cdma2000, which first appeared with the publication of the IS-2000 Release 0 in 1999. Release A version of IS-2000 was published in mid 2000 with the inclusion of additional signaling support for features such as new common channels, Quality-of-Service (QoS) negotiation, enhanced authentication, encryption and concurrent services. The cdma2000 system was designed to be backward compatible with existing cdmaOne networks and voice terminals.
Several CDMA-based standards and their relation to the harmonized third generation (3G) mobile communication systems have been developed and endorsed by the International Telecommunications Union (ITU) and known as IMT-2000. Both Time Division Duplex (TDD) and Frequency Division Duplex (FDD) modes are supported by IMT-2000. The more common FDD mode uses different frequency bands for the uplink and downlink carriers separated by a fixed frequency, while TDD systems use the same frequency band for both uplink and downlink. The downlink is the communications link from the base station to the user terminal. The uplink is the communications link from the user terminal to base station.
The 3rd Generation Partnership Project (3GPP) is a collaboration agreement that was established in December 1998. Initially, the scope of 3GPP was to produce globally applicable Technical Specifications and Technical Reports for a 3rd Generation Mobile System. The scope was subsequently amended to include the maintenance and development of the Global System for Mobile communication (GSM) Technical Specifications and Technical Reports including evolved radio access technologies (e.g. General Packet Radio Service (GPRS) and Enhanced Data rates for GSM Evolution (EDGE)), WCDMA, etc.
Various types of services have been developed and implemented in various systems which operate based on the various standards mentioned above. For example, Mutimedia Broadcast/Multicast Service (MBMS) is a service that is (1) one base station to many user terminals and (2) unbalanced towards the downlink in that there is a higher data rate transmission on the downlink as compared to on the uplink. As such, in general the MBMS users do not provide any sort of feedback including feedback information or feedback messages to the network. However, if a feedback (even low data rate) were possible, this would be surely beneficial for the system. The advantages of the feedback include the ability for the system to retransmit lost data packets as well to adapt the data transmission to the operating conditions. There is therefore a need for user terminals (also called mobile stations or MS herein) to signal multicast/broadcast service quality and provide feedback on a statistical basis or on a per-event basis.